The present invention relates to commercial cooking and refrigeration equipment. Specifically, the present invention relates to an insulated cabinet, interchangeable heating or refrigeration units which can be connected with the cabinet, and an improved connection for channeling air from the heating or cooling units and distributing it within the cabinet.
In the past it has been proposed to build insulated cabinets for use in commercial kitchens or by caterers to which may be attached any of a number of heat transfer units. Typically the cabinets stand about six feet tall and are approximately two feet wide. Both shorter and wider cabinets are available. Shelves are easily installed at different levels within the cabinet to accommodate food items of different heights. It is intended that a large number of food products be accommodated simultaneously, for example dozens of loaves of bread or a large number of roasts.
The heat transfer units which fit on top of the cabinets may be refrigeration or freezer units, warming units or baking units, among others. Each of the heat transfer units includes an air intake, a fan or fans, a heating or cooling device to transfer heat to or from the air, and an outlet for heated or cooled air. The units are intended to be positioned over and sealed against an opening in the top of the cabinet. The air inlet then communicates directly with the cabinet interior while the treated air outlet communicates with a vertically extending tunnel on the rear wall of the cabinet. The fan(s) draws air from the intake, forces it past the heating or cooling device, through the outlet, into the tunnel, and then through many louvers in the tunnel walls into the interior of the cabinet.
The outlet of prior art heating or cooling units is formed by a rectangular opening in the bottom or floor of a chamber in which the heating elements or refrigeration evaporator are located. A short, parallelsided duct makes an extension of the rectangular opening and leads to the top of the tunnel which has a slightly larger rectangular cross section than the duct so that the end portion of the duct fits inside the top of the tunnel.
The tunnel is made of sheet metal and extends vertically along the cabinet back with louvers in the front face and perforations in the side walls. The back of the cabinet closes the back of the tunnel. Vertically, the tunnel is divided by the pattern of louvers, a single column of louvers being formed in the top half of the tunnel's front wall, and a double column of louvers being formed in the bottom half of the tunnel's front wall. A baffle plate for diffusing heated or cooled air exiting from the louvers is located in front of the tunnel wall. The baffle plate has a solid central portion and perforations along vertically extending edge portions. Heated or cooled air exiting the tunnel through the louvers and the side wall perforations of the tunnel pass through the perforations on the lateral edge portions of the baffle and into the interior of the cabinet.
Even distribution of air is important for proper operation of devices of this sort, especially where the heat transfer unit is a heating unit and the device is operated as an oven. Within the cabinet itself uniform air flow is important to even cooking of the foods within. Where there are substantial temperature variations between the top and bottom of the cabinet, foods on the bottom shelf will be cooked in a different length of time from foods on the top shelf, possibly with distasteful results.
Of equal concern is air flow over the heating elements themselves. If there are stagnant pockets or corners surrounding the heating elements where the air flows less rapidly than elsewhere, the heating elements may overheat, shortening their lifespan appreciably.